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UNITED STATES PATENT OFFICE.

HENRY JOHNS, OF NEW YORK, N. Y.

PROCESS OF DEMAGN'ETIZING AS BE STUS.

SPECIFICATION forming part of Letters Patent No. 461,579, dated October 20, 1891.

Application filed March 28, 1891. Serial No. 386,845. (No specimens.)

T0 to whom, it may concern.-

Be itknown thatI, HENRY \V. JOHNS, a citizen of the United States, and a resident of New York city, in the county of New York and State of New York, have invented a certain new and useful product or manufacturei. a, the Process of Demagnetizing Asbestus-of which the following is a specification.

My invention consists in a new and improved process for the manufacture or production of demagn etized asbestus. For along time there has existed a demand for such a product,it being useful for Various manufactures, and various attempts have been made to demagnetize asbestus, no method, so far as I am aware, having been successful. It has been attempted to dissolve the iron by subj ecting the asbestus to the action of an acid or a combination of acids. The result of this process has been exceedingly unsatisfactory and has resulted in the destruction of the asbestus fiber because the acids not only dissolve, or rather partially dissolve, the magnetite, but also dissolve the silex and the magnesia, which are the main constituents of asbestus, so that the resulting product is not properly asbestus at all. In other words, all the strength and vitality and most of the constituent elements of the asbestus having been destroyed or modified by the action of the acids, there remained nothing but a pulpy mass, which could be molded into certain forms, it is true, but which had no strength or fiber and was useless for the purposes for which demagnetized asbestus is mainly desired.

As the acid process has proved unsuccessf ul, it is now the practice to remove the magnetite from asbestus manually by picking out one by one the iron particles. This is an ex-,

ceedingly laborious and expensive process.

By my invention I quickly, easily, and in a very efiective manner remove the magnetite, and I do not alter in any respect the several constituents of the asbestus.

I proceed as follows: First I crush the asbestus and reduce it to a loose fiber. During the crushingprocessthe magnetite is loosened; but it remains in the mass. I then subject this mass to violent agitation in a chest or box with an opening at each end-that is to say, I feed it to a suitably-constructed machine by any suitable device and subject it to the action of any suitable disintegrating device, such as an opener, a picker,arapidly- During this operation the particles by gravity, drop to the bottom of the box or machine, and the fine fibers, free from mag-- netite, are carried over the end of the machine.

In case any fine particles of magnetite should be retained by the asbestus, I sometimes assist the action of gravity by placing in the bottom of the box or of an additional box of similar construction or projecting up into it and extending across the box from side to side, or otherwise, as preferred, a series of strong magnets. magnets or electro-magnets, and they may be stationary, but are preferably movable upon ,a belt or equivalent device, so that as they become coated with the particles of iron they These may be permanent may be automatically cleaned. In this way,

there being a sufficient length or area of magnets relative to the quantity of the asbestus fiber passed through the box, all the particles of magnetite, even in the form of dust, are

drawn to and held by the magnets; but the asbestus fiber, entirely freed from the magnetite, goes over into a suitable receptacle.

It will be observed that this process, whether the magnets are used or not, is a mechanical,

not a chemical, process, and that I do not in 0 any way affect the asbestus except to remove the magnetite.

The perfect result I have attained is largely due to the construction of the separating or fibering machine, which of itself almost com- 5 pletely removes the magnetite, and which I do not herein claim nor describe more fully because that is to form the subject-matter of another application for Letters Patent.

I claim- TOO 1. The mechanical process herein described ofdemagnetizingasbestus,consistingincrushing or fibering the asbestus and then subjecting the mass while under agitation t0 the action of an air-blast, substantially as set forth.

2. The mechanical process herein described of demagnctizingasbestns, consistingin crnshing or fibering the asbestus and then subjecting the mass while under agitation to the ac- 

